Procédé pour la préparation de nouveaux antibiotiques, les polyoxines A et B

Polyoxin complex, an antifungal antibiotic, having components A and B, is prepared by cultivating a polyoxin-producing strain of Streptomyces cacavi var. asoensis, e.g. ATCC 19093 or ATCC 19094 in a culture medium containing assimilable sources of C, N and inorganic salts, preferably under submerged aerobic conditions. The complex may be isolated from the clarified broth by adsorption on activated carbon at acidic or neutral pH, followed by elution with aqueous acetone or aqueous ethanol. Further purification is by adsorption on cationic or anionic exchange resins followed by elution with acid, alkali or salt solutions, e.g. aqueous sodium chloride or phosphate buffer of pH 4.3, followed by chromatography on sulphoethyl Sephadex, sulphoethylcellulose or sulphomethylcellulose. The polyoxin complex is separated into polyoxin A and polyoxin B by (a) distribution chromatography using cellulose powder or silica gel and the solvent system butanol, acetic acid and water (4 : 1 : 2), or (b) fractional crystallization from aqueous solvents. The A and B components may be further purified by zone electrophoresis.